Communications system providing server load balancing based upon load and separation metrics and related methods

ABSTRACT

A communications system may include a plurality of client devices configured to generate client processing jobs, each having a respective unique client ID associated therewith. A plurality of geographically spaced apart servers may be configured to process the client processing jobs, each having a respective unique server ID associated therewith. A load balancer may be configured to receive the client processing jobs from the plurality of client devices, and for each client processing job, generate a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server. The load balancer may also be configured to assign each client processing job to a respective server based upon the load balancing scores.

TECHNICAL FIELD

This application relates to the field of communications systems, and more particularly, to load balancing within communication or network systems and related methods.

BACKGROUND

Mobile communication systems continue to grow in popularity and have become an integral part of both personal and business communications. Various mobile devices now incorporate Personal Digital Assistant (PDA) features such as calendars, address books, task lists, calculators, memo and writing programs, media players, games, etc. These multi-function devices usually allow electronic mail (email) messages to be sent and received wirelessly, as well as access the Internet via a cellular network and/or a wireless local area network (WLAN), for example.

With the continuing migration to mobile devices that generate these types of client jobs (i.e., Internet access requests, email processing jobs, etc.), there is a commensurate growth in the number of such jobs that service providers have to accommodate. This is in addition to the ever increasing number of client processing jobs generated by other client devices, such as desktop computers. While service providers continue to add additional data centers and servers to accommodate increasing processing loads, routing client jobs to appropriate data centers, and even servers within a given data center, to provide desired efficiencies is important.

As such, some form of load balancing is generally used to even out the processing load among different servers or data centers in communications systems. By way of example, one basic form of load balancing is round-robin load balancing. In accordance with this approach, the servers are arranged in some order, and client jobs are sequentially assigned to the next server in the order until the end is reached, and the process repeats from the beginning. Another load balancing approach is the least load approach, which simply means that when a new client job is received it is assigned to the system server which currently has the least or lightest processing load.

Another form of routing is hash routing. For example, typical hash routing may utilize hashes generated from source and destination addresses of a given job to assign a score or value for the given source-destination pair. By picking a highest or lowest score, for example, this arbitrarily assigns client jobs to respective servers.

Despite the advantages of such approaches, further techniques for load balancing among relatively large groups of servers would be useful in certain applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a communications system in accordance with an example embodiment providing enhanced load balancing techniques.

FIGS. 2 and 3 are flow diagrams illustrating method aspects associated with the system of FIG. 1.

FIG. 4 is a block diagram of an example embodiment of a mobile device that may be used with the system of FIG. 1.

FIG. 5 is a block diagram of an example embodiment of a communication subsystem component of the mobile device of FIG. 4.

FIG. 6 is an example block diagram of a node of a wireless network.

FIG. 7 is a block diagram illustrating components of a host system in one example configuration for use with the wireless network of FIG. 6 and the mobile device of FIG. 4.

DETAILED DESCRIPTION

The present description is made with reference to the accompanying drawings, in which example embodiments are shown. However, many different embodiments may be used, and thus the description should not be construed as limited to the embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements or steps in alternative example embodiments.

Generally speaking, a communications system is disclosed herein which may include a plurality of client devices configured to generate client processing jobs and each having a respective unique client identification (ID) associated therewith. The system may further include a plurality of geographically spaced apart servers configured to process the client processing jobs, and each having a respective unique server ID associated therewith. Moreover, the system may additionally include a load balancer configured to receive the client processing jobs from the plurality of client devices, and for each client processing job, generate a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server. The load balancer may also be configured to assign each client processing job to a respective server based upon the load balancing scores for the client processing job. Accordingly, the load balancer may usefully provide a preference to servers that have a relatively small separation with respect to a given client device, yet still account for server load to provide enhanced performance.

By way of example, the separation metric may correspond to a number of network nodes between the requesting client device and each server, a geographic distance between the requesting client device and each server, or a network latency between the requesting client device and each server. Furthermore, the load balancer may be configured to generate the respective load balancing score for each server based upon a hash of the client ID, the separation metric, and a hash of the server ID and the processing load metric.

In addition, the load balancer may be configured to assign each client processing job to a respective server having a lowest load balancing score from among the load balancing scores for the client processing job. By way of example, the processing jobs may comprise Internet access jobs. Further, at least some of the plurality of client devices may comprise mobile wireless communications devices, such as cellular devices, for example.

A related load balancer may be for use with a plurality of client devices configured to generate client processing jobs and each having a respective unique client ID associated therewith, and a plurality of geographically spaced apart servers configured to process the client processing jobs and each having a respective unique server ID associated therewith. The load balancer may include a client device interface module configured to receive the client processing jobs from the plurality of client devices, and a server interface module coupled to the client device interface module. The server interface module may be configured to, for each client processing job, generate a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server. The server interface module may also be configured to assign each client processing job to a respective server based upon the load balancing scores for the client processing job.

A related load balancing method may be for a plurality of client devices configured to generate client processing jobs and each having a respective unique client ID associated therewith, and a plurality of geographically spaced apart servers configured to process the client processing jobs and each having a respective unique server ID associated therewith. The method may include receiving the client processing jobs from the plurality of client devices at a client device interface module. Furthermore, for each client processing job, a respective load balancing score may be generated for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server at a server interface module. The method may further include assigning each client processing job to a respective server at the server interface module based upon the load balancing scores for the client processing job.

FIG. 1 is a schematic block diagram of a communication system in accordance with an example embodiment providing load balancing techniques. FIGS. 2-3 are flow diagrams each illustrating example embodiment methods associated with the system of FIG. 1. In FIG. 1, a communications system 30 illustratively includes a plurality of client devices 31 a-31 n, which are configured to generate client processing jobs such as Internet access requests, email processing jobs, calendar or address book synchronization jobs, etc. At Block 50 of FIG. 2 and Block 50′ of FIG. 3, each method starts. In the present examples, the client device 31 a is a mobile wireless communications device (i.e., a mobile device), namely a cellular device which generates and communicates its client processing jobs to a load balancer 32 via a wireless communications network 33 (illustratively represented as a cellular tower in FIG. 1) at Block 51 of FIG. 2 and Block 51′ of FIG. 3. The client device 30 b is a desktop computer, and the client device 31 n is a laptop computer. In this example, the client processing (CP) jobs are wide area network 37 (e.g., Internet) access jobs, as will be appreciated by those skilled in the art.

Each of the client devices 31 a-31 n has a respective unique client identification (ID) associated therewith. For example, with the mobile device 31 a the client ID may be an International Mobile Equipment Identity (IMEI) number. With respect to the client devices 31 b, 31 n, the client IDs may be respective Internet protocol (IP) addresses, for example. Other suitable types of client IDs may also be used, as will be appreciated by those skilled in the art.

The system 30 further illustratively includes a plurality of geographically spaced apart servers 34 a-34 n which are configured to process the client processing jobs. By way of example, the servers 34 a-34 n may be located in different data centers. Similar to the client devices 31 a-31 n, each of the servers 34 a-34 n also has a respective unique server ID associated therewith. Here again, the server IDs may be IP addresses, although other suitable ID types may also be used.

The load balancer 32 illustratively includes a client device interface module 35 configured to receive the client processing jobs from the plurality of client devices 31 a-31 b, at Block 52 of FIG. 2 and Block 52′ of FIG. 3. The load balancer 32 further illustratively includes a server interface module 36 which cooperates with the client device interface module 35 and is configured to perform load balancing for the received client jobs. More particularly, for each client processing job, the server interface module 36 generates a respective load balancing score for each server 34 a-34 n, at Block 53 of FIG. 2. Each load balancing score is based upon the client ID of the client device 31 a-31 n requesting the client processing job, the server ID of each server 34 a-34 n, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server.

By way of example, the separation metric may correspond to a number of network nodes between the requesting client device 31 a-31 n and each server 34 a-34 n, a geographic distance between the requesting client device and each server, a network latency between the requesting client device and each server or other time or distance-based metric which can differentiate a pair of a requesting client device and a server from another pair of a requesting client device and a sever. Furthermore, in example embodiments, the processing load metric indicates a processing load for each server 34 a-34 n, and may be based upon one or more factors including a number of pending client jobs, available memory, processing speed, etc., as will be appreciated by those skilled in the art.

At Block 53′ of FIG. 3, in accordance with one example approach, the server interface module 36 generates the respective load balancing score for each server as follows:

srv_hash=f(h(server ID),load metric); and

Score=g(client ID,srv_hash,separation metric).

In other words, srv_hash is a function based upon h(Server ID), a hash of the server ID of the given server 34 a-34 n, and a load balancing metric. Score is the load balancing score and it is based on a function of the client ID, srv_hash, and a separation metric. Another example approach is that the srv_hash function may be based on a function of a hash of both the server ID and the load metric, as opposed to a function of the load metric and a hash of the server ID by itself.

In accordance with the example implementation, the packet router 32 computes (or pre-computes upon server connection) the srv_hash function for each connected server 34 a-34 n, which it stores in a hash table, etc., to reduce packet routing time. Incoming client processing jobs (which may be in the form of packets) are passed through the Score function g(client ID, srv_hash, separation metric) for each connected server 34 a-34 n to compute a load balancing score for each server. The functions f( ) and g( ) may be chosen such that the separation and load weighting is proportional, although this need not be the case in all example embodiments. Example functions for f( ) and g( ) are discussed further below. By way of example, these may also be hash functions in some example embodiments. In accordance with an example embodiment, the processing job is assigned to the server 34 with the highest score, although in some implementations different functions may be used such that the lowest score is appropriate, for example.

Various hashing functions known to those skilled in the art may be used, such as cyclic redundancy checks, checksum functions, cryptographic hash functions, etc. A consideration for the particular hashing (or other) function to be used is that it returns a consistent result each time a given ID is hashed therewith, as opposed to providing a pseudo-random result. As noted above, hash values for the servers 34 a-34 n (and, optionally, the client devices 31 a-31 n) may be generated before hand and stored in a hash table, if desired, to expedite determination of the load balancing scores as new client processing jobs are received.

The server interface module 36 is configured to assign each client processing job to a respective one of the servers 34 a-34 n based upon the load balancing scores for the client processing job, at Block 54 of FIG. 2 and Block 54′ of FIG. 3, as described above, and the job is then forwarded to and processed by the respective server, at Block 55 of FIG. 2 and Block 55′ of FIG. 3, thus concluding the method illustrated in FIG. 2 (Block 56). Using the above-described load balancing approach, the load balancer 32 may usefully provide a preference to servers 34 a-34 n that have a relatively small separation with respect to a given one of the client devices 31 a-31 n, yet still account for server load to provide enhanced performance. That is, the load balancing will tend to “default” to one of servers 34 a-34 n that has the lowest separation to the given client device 31, unless that server is highly loaded.

As noted above, the client processing jobs may be formatted in packets. The load balancer 32 may therefore be implemented as a packet router. The packet router will have information about the clients 31 a-31 n, including their unique client IDs. For example, the incoming packets may be tagged with the client IDs. Moreover, the packet router also has (or determines) information about the destination servers 34 a-34 n, including their unique server IDs, processing load metrics, and separation metrics. The packet router will perform the above-described hash-based function on each client-server pair, giving each pair a score. Once the packet router has calculated the function for each client-server pair, the client processing job is routed to the highest (or, in some example embodiments, lowest) scoring server, as appropriate for the given hashing function. Again, this provides a mechanism such that servers 34 a-34 n with the least separation are more likely to be routed to, given equal load factors. It also provides that servers 34 a-34 n which are further separated will continue to be routed to if the loads are sufficiently high on more closely separated servers.

An example Java algorithm for implementing the above-described hash function approach is as follows:

  Map map; function server_connect (ServerID, weight, ...) {  map [ServerID] = f(ServerID, weight); } function choose_server(clientPacket, clientID) {  int max_score = −1;  server chosen_server = null;  for server_value in map; do {   if (serverID.connected == false)    break;   cur_score = g (server_value, clientID,    separation (serverID, clientID));   if (cur_score > max_score) {    max_score = cur_score;    chosen_server = serverID;   }  }  return chosen_server; } function f (ServerID id, Weight w) {  // This may be a O (1) function which  // distributes id's and weights among a fairly large (integer)  // number-space. It will return an integer which can be used for  // future client-server hash calculations. } function g(hash h, ClientID id, Separation d) {  // This may be a O (1) function which  // provides a fairly large variance when considering many  // client ID's and server hashes, such that when computing  // many scores, there will be a large distribution across  // the (integer) number-space. } function separation(ServerID s_id, ClientID c_id) {  // Function returns the relative separation between the client  // and server. This may be a function of server alone, or  // a combination of server and packet router, or client, server  // and packet router }

The hashing functions srv_hash=f(ServerID, load) and Score=g(hash, ClientID, separation) above may be implemented in various ways to best distribute the traffic depending on the given application. For example, the Fowler-Noll-Vo hash function may be employed and modified as follows:

  public class FnvHash {  private static final int kFNVOffset = (int) 21661362611;  private static final int kFNVPrime = 16777619;  public static long fnvHashCode(final String str) {   int hash = kFNVOffset;   for (int i = 0; i < str.length( ); i ++) {    hash {circumflex over ( )}= (0x0000ffff & (int)str.charAt(i));    hash *= kFNVPrime;   }   return 0x00000000ffffffffl & (long) hash;  }  public static long server_hash (String serverlD, int weight) {   return (fnvHashCode (serverID) *weight);  }  public static long client_hash (long server_hash, String clientID, int separation) {   long client_hash = fnvHashCode(clientID);   long comb_hash = (client_hash << 16) {circumflex over ( )} server_hash;   comb_hash = comb_hash >> (separation-1);   return (comb_hash);  }

This particular implementation has upper and lower bounds on load (i.e., load>0) and bounds on separation (since Java longs are 64 bytes). In the above example, the load metric is referred to as “weight”.

Example components of a mobile wireless communications device that may be used in accordance with an example embodiment are further described below with reference to FIGS. 4-7. Generally speaking, a mobile device may be configured according to an IT policy. It should be noted that the term IT policy, in general, refers to a collection of IT policy rules, in which the IT policy rules can be defined as being either grouped or non-grouped and global or per-user. The terms grouped, non-grouped, global and per-user are defined further below. Examples of applicable communication devices include pagers, cellular phones, cellular smart-phones, wireless organizers, personal digital assistants, computers, laptops, handheld wireless communication devices, wirelessly enabled notebook computers and the like.

The mobile device is a two-way communication device with advanced data communication capabilities including the capability to communicate with other mobile devices or computer systems through a network of transceiver stations. The mobile device may also have the capability to allow voice communication. Depending on the functionality provided by the mobile device, it may be referred to as a data messaging device, a two-way pager, a cellular telephone with data messaging capabilities, a wireless Internet appliance, or a data communication device (with or without telephony capabilities). To aid the reader in understanding the structure of the mobile device and how it communicates with other devices and host systems, reference will now be made to FIGS. 4-7.

Referring first to FIG. 4, shown therein is a block diagram of an example embodiment of a mobile device 100. The mobile device 100 includes a number of components such as a main processor 102 that controls the overall operation of the mobile device 100. Communication functions, including data and voice communications, are performed through a communication subsystem 104. The communication subsystem 104 receives messages from and sends messages to a wireless network 200. In this example embodiment of the mobile device 100, the communication subsystem 104 is configured in accordance with the Global System for Mobile Communication (GSM) and General Packet Radio Services (GPRS) standards. The GSM/GPRS wireless network is used worldwide and it is expected that these standards will be superseded eventually by Enhanced Data GSM Environment (EDGE) and Universal Mobile Telecommunications Service (UMTS). New standards are still being defined, but it is believed that they will have similarities to the network behavior described herein, and it will also be understood by persons skilled in the art that the example embodiments described herein are intended to use any other suitable standards that are developed in the future. The wireless link connecting the communication subsystem 104 with the wireless network 200 represents one or more different Radio Frequency (RF) channels, operating according to defined protocols specified for GSM/GPRS communications. With newer network protocols, these channels are capable of supporting both circuit switched voice communications and packet switched data communications.

Although the wireless network 200 associated with mobile device 100 is a GSM/GPRS wireless network in one example implementation, other wireless networks may also be associated with the mobile device 100 in variant implementations. The different types of wireless networks that may be employed include, for example, data-centric wireless networks, voice-centric wireless networks, and dual-mode networks that can support both voice and data communications over the same physical base stations. Combined dual-mode networks include, but are not limited to, Code Division Multiple Access (CDMA) or CDMA2000 networks, GSM/GPRS networks (as mentioned above), and future third-generation (3G) networks like EDGE and UMTS. Some other examples of data-centric networks include WiFi 802.11, Mobitex™ and DataTAC^(TS) network communication systems. Examples of other voice-centric data networks include Personal Communication Systems (PCS) networks like GSM and Time Division Multiple Access (TDMA) systems.

The main processor 102 also interacts with additional subsystems such as a Random Access Memory (RAM) 106, a flash memory 108, a display 110, an auxiliary input/output (I/O) subsystem 112, a data port 114, a keyboard 116, a speaker 118, a microphone 120, short-range communications 122 and other device subsystems 124.

Some of the subsystems of the mobile device 100 perform communication-related functions, whereas other subsystems may provide “resident” or on-device functions. By way of example, the display 110 and the keyboard 116 may be used for both communication-related functions, such as entering a text message for transmission over the network 200, and device-resident functions such as a calculator or task list.

The mobile device 100 can send and receive communication signals over the wireless network 200 after required network registration or activation procedures have been completed. Network access is associated with a subscriber or user of the mobile device 100. To identify a subscriber, the mobile device 100 requires a SIM/RUIM card 126 (i.e., Subscriber Identity Module or a Removable User Identity Module) to be inserted into a SIM/RUIM interface 128 in order to communicate with a network. The SIM card or RUIM 126 is one type of a conventional “smart card” that can be used to identify a subscriber of the mobile device 100 and to personalize the mobile device 100, among other things. Without the SIM card 126, the mobile device 100 is not fully operational for communication with the wireless network 200. By inserting the SIM card/RUIM 126 into the SIM/RUIM interface 128, a subscriber can access all subscribed services. Services may include: web browsing and messaging such as email, voice mail, Short Message Service (SMS), and Multimedia Messaging Services (MMS). More advanced services may include: point of sale, field service and sales force automation. The SIM card/RUIM 126 includes a processor and memory for storing information. Once the SIM card/RUIM 126 is inserted into the SIM/RUIM interface 128, it is coupled to the main processor 102. In order to identify the subscriber, the SIM card/RUIM 126 can include some user parameters such as an International Mobile Subscriber Identity (IMSI). An advantage of using the SIM card/RUIM 126 is that a subscriber is not necessarily bound by any single physical mobile device. The SIM card/RUIM 126 may store additional subscriber information for a mobile device as well, including date book (or calendar) information and recent call information. Alternatively, user identification information can also be programmed into the flash memory 108.

The mobile device 100 is a battery-powered device and includes a battery interface 132 for receiving one or more rechargeable batteries 130. In at least some example embodiments, the battery 130 can be a smart battery with an embedded microprocessor. The battery interface 132 is coupled to a regulator (not shown), which assists the battery 130 in providing power V+ to the mobile device 100. Although current technology makes use of a battery, future technologies such as micro fuel cells may provide the power to the mobile device 100.

The mobile device 100 also includes an operating system 134 and software components 136 to 146 which are described in more detail below. The operating system 134 and the software components 136 to 146 that are executed by the main processor 102 are typically stored in a persistent store such as the flash memory 108, which may alternatively be a read-only memory (ROM) or similar storage element (not shown). Those skilled in the art will appreciate that portions of the operating system 134 and the software components 136 to 146, such as specific device applications, or parts thereof, may be temporarily loaded into a volatile store such as the RAM 106. Other software components can also be included, as is well known to those skilled in the art.

The subset of software applications 136 that control basic device operations, including data and voice communication applications, will normally be installed on the mobile device 100 during its manufacture. Other software applications include a message application 138 that can be any suitable software program that allows a user of the mobile device 100 to send and receive electronic messages. Various alternatives exist for the message application 138 as is well known to those skilled in the art. Messages that have been sent or received by the user are typically stored in the flash memory 108 of the mobile device 100 or some other suitable storage element in the mobile device 100. In at least some example embodiments, some of the sent and received messages may be stored remotely from the device 100 such as in a data store of an associated host system that the mobile device 100 communicates with.

The software applications can further include a device state module 140, a Personal Information Manager (PIM) 142, and other suitable modules (not shown). The device state module 140 provides persistence, i.e., the device state module 140 ensures that important device data is stored in persistent memory, such as the flash memory 108, so that the data is not lost when the mobile device 100 is turned off or loses power.

The PIM 142 includes functionality for organizing and managing data items of interest to the user, such as, but not limited to, email, contacts, calendar events, voice mails, appointments, and task items. A PIM application has the ability to send and receive data items via the wireless network 200. PIM data items may be seamlessly integrated, synchronized, and updated via the wireless network 200 with the mobile device subscriber's corresponding data items stored and/or associated with a host computer system. This functionality creates a mirrored host computer on the mobile device 100 with respect to such items. This can be particularly advantageous when the host computer system is the mobile device subscriber's office computer system.

The mobile device 100 also includes a connect module 144, and an IT policy module 146. The connect module 144 implements the communication protocols that are required for the mobile device 100 to communicate with the wireless infrastructure and any host system, such as an enterprise system, that the mobile device 100 is authorized to interface with. Examples of a wireless infrastructure and an enterprise system are given in FIGS. 6 and 7, which are described in more detail below.

The connect module 144 includes a set of APIs that can be integrated with the mobile device 100 to allow the mobile device 100 to use any number of services associated with the enterprise system. The connect module 144 allows the mobile device 100 to establish an end-to-end secure, authenticated communication pipe with the host system. A subset of applications for which access is provided by the connect module 144 can be used to pass IT policy commands from the host system to the mobile device 100. This can be done in a wireless or wired manner. These instructions can then be passed to the IT policy module 146 to modify the configuration of the device 100. Alternatively, in some cases, the IT policy update can also be done over a wired connection.

The IT policy module 146 receives IT policy data that encodes the IT policy. The IT policy module 146 then ensures that the IT policy data is authenticated by the mobile device 100. The IT policy data can then be stored in the flash memory 106 in its native form. After the IT policy data is stored, a global notification can be sent by the IT policy module 146 to all of the applications residing on the mobile device 100. Applications for which the IT policy may be applicable then respond by reading the IT policy data to look for IT policy rules that are applicable.

The IT policy module 146 can include a parser (not shown), which can be used by the applications to read the IT policy rules. In some cases, another module or application can provide the parser. Grouped IT policy rules, described in more detail below, are retrieved as byte streams, which are then sent (recursively, in a sense) into the parser to determine the values of each IT policy rule defined within the grouped IT policy rule. In at least some example embodiments, the IT policy module 146 can determine which applications are affected by the IT policy data and send a notification to only those applications. In either of these cases, for applications that aren't running at the time of the notification, the applications can call the parser or the IT policy module 146 when they are executed to determine if there are any relevant IT policy rules in the newly received IT policy data.

All applications that support rules in the IT Policy are coded to know the type of data to expect. For example, the value that is set for the “WEP User Name” IT policy rule is known to be a string; therefore the value in the IT policy data that corresponds to this rule is interpreted as a string. As another example, the setting for the “Set Maximum Password Attempts” IT policy rule is known to be an integer, and therefore the value in the IT policy data that corresponds to this rule is interpreted as such.

After the IT policy rules have been applied to the applicable applications or configuration files, the IT policy module 146 sends an acknowledgement back to the host system to indicate that the IT policy data was received and successfully applied.

Other types of software applications can also be installed on the mobile device 100. These software applications can be third party applications, which are added after the manufacture of the mobile device 100. Examples of third party applications include games, calculators, utilities, etc.

The additional applications can be loaded onto the mobile device 100 through at least one of the wireless network 200, the auxiliary I/O subsystem 112, the data port 114, the short-range communications subsystem 122, or any other suitable device subsystem 124. This flexibility in application installation increases the functionality of the mobile device 100 and may provide enhanced on-device functions, communication-related functions, or both. For example, secure communication applications may enable electronic commerce functions and other such financial transactions to be performed using the mobile device 100.

The data port 114 enables a subscriber to set preferences through an external device or software application and extends the capabilities of the mobile device 100 by providing for information or software downloads to the mobile device 100 other than through a wireless communication network. The alternate download path may, for example, be used to load an encryption key onto the mobile device 100 through a direct and thus reliable and trusted connection to provide secure device communication.

The data port 114 can be any suitable port that enables data communication between the mobile device 100 and another computing device. The data port 114 can be a serial or a parallel port. In some instances, the data port 114 can be a USB port that includes data lines for data transfer and a supply line that can provide a charging current to charge the battery 130 of the mobile device 100.

The short-range communications subsystem 122 provides for communication between the mobile device 100 and different systems or devices, without the use of the wireless network 200. For example, the subsystem 122 may include an infrared device and associated circuits and components for short-range communication. Examples of short-range communication standards include standards developed by the Infrared Data Association (IrDA), Bluetooth, and the 802.11 family of standards developed by IEEE.

In use, a received signal such as a text message, an email message, or web page download will be processed by the communication subsystem 104 and input to the main processor 102. The main processor 102 will then process the received signal for output to the display 110 or alternatively to the auxiliary I/O subsystem 112. A subscriber may also compose data items, such as email messages, for example, using the keyboard 116 in conjunction with the display 110 and possibly the auxiliary I/O subsystem 112. The auxiliary subsystem 112 may include devices such as: a touch screen, mouse, track ball, infrared fingerprint detector, or a roller wheel with dynamic button pressing capability. The keyboard 116 is preferably an alphanumeric keyboard and/or telephone-type keypad. However, other types of keyboards may also be used. A composed item may be transmitted over the wireless network 200 through the communication subsystem 104.

For voice communications, the overall operation of the mobile device 100 is substantially similar, except that the received signals are output to the speaker 118, and signals for transmission are generated by the microphone 120. Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, can also be implemented on the mobile device 100. Although voice or audio signal output is accomplished primarily through the speaker 118, the display 110 can also be used to provide additional information such as the identity of a calling party, duration of a voice call, or other voice call related information.

Referring now to FIG. 5, an example block diagram of the communication subsystem component 104 is shown. The communication subsystem 104 includes a receiver 150, a transmitter 152, as well as associated components such as one or more embedded or internal antenna elements 154 and 156, Local Oscillators (LOs) 158, and a processing module such as a Digital Signal Processor (DSP) 160. The particular design of the communication subsystem 104 is dependent upon the communication network 200 with which the mobile device 100 is intended to operate. Thus, it should be understood that the design illustrated in FIG. 5 serves only as one example.

Signals received by the antenna 154 through the wireless network 200 are input to the receiver 150, which may perform such common receiver functions as signal amplification, frequency down conversion, filtering, channel selection, and analog-to-digital (A/D) conversion. A/D conversion of a received signal allows more complex communication functions such as demodulation and decoding to be performed in the DSP 160. In a similar manner, signals to be transmitted are processed, including modulation and encoding, by the DSP 160. These DSP-processed signals are input to the transmitter 152 for digital-to-analog (D/A) conversion, frequency up conversion, filtering, amplification and transmission over the wireless network 200 via the antenna 156. The DSP 160 not only processes communication signals, but also provides for receiver and transmitter control. For example, the gains applied to communication signals in the receiver 150 and the transmitter 152 may be adaptively controlled through automatic gain control algorithms implemented in the DSP 160.

The wireless link between the mobile device 100 and the wireless network 200 can contain one or more different channels, typically different RF channels, and associated protocols used between the mobile device 100 and the wireless network 200. An RF channel is a limited resource that must be conserved, typically due to limits in overall bandwidth and limited battery power of the mobile device 100.

When the mobile device 100 is fully operational, the transmitter 152 is typically keyed or turned on only when it is transmitting to the wireless network 200 and is otherwise turned off to conserve resources. Similarly, the receiver 150 is periodically turned off to conserve power until it is needed to receive signals or information (if at all) during designated time periods.

Referring now to FIG. 6, a block diagram of an example implementation of a node 202 of the wireless network 200 is shown. In practice, the wireless network 200 includes one or more nodes 202. In conjunction with the connect module 144, the mobile device 100 can communicate with the node 202 within the wireless network 200. In the example implementation of FIG. 6, the node 202 is configured in accordance with General Packet Radio Service (GPRS) and Global Systems for Mobile (GSM) technologies. The node 202 includes a base station controller (BSC) 204 with an associated tower station 206, a Packet Control Unit (PCU) 208 added for GPRS support in GSM, a Mobile Switching Center (MSC) 210, a Home Location Register (HLR) 212, a Visitor Location Registry (VLR) 214, a Serving GPRS Support Node (SGSN) 216, a Gateway GPRS Support Node (GGSN) 218, and a Dynamic Host Configuration Protocol (DHCP) 220. This list of components is not meant to be an exhaustive list of the components of every node 202 within a GSM/GPRS network, but rather a list of components that are commonly used in communications through the network 200.

In a GSM network, the MSC 210 is coupled to the BSC 204 and to a landline network, such as a Public Switched Telephone Network (PSTN) 222 to satisfy circuit switched requirements. The connection through the PCU 208, the SGSN 216 and the GGSN 218 to a public or private network (Internet) 224 (also referred to herein generally as a shared network infrastructure) represents the data path for GPRS capable mobile devices. In a GSM network extended with GPRS capabilities, the BSC 204 also contains the Packet Control Unit (PCU) 208 that connects to the SGSN 216 to control segmentation, radio channel allocation and to satisfy packet switched requirements. To track the location of the mobile device 100 and availability for both circuit switched and packet switched management, the HLR 212 is shared between the MSC 210 and the SGSN 216. Access to the VLR 214 is controlled by the MSC 210.

The station 206 is a fixed transceiver station and together with the BSC 204 form fixed transceiver equipment. The fixed transceiver equipment provides wireless network coverage for a particular coverage area commonly referred to as a “cell.” The fixed transceiver equipment transmits communication signals to and receives communication signals from mobile devices within its cell via the station 206. The fixed transceiver equipment normally performs such functions as modulation and possibly encoding and/or encryption of signals to be transmitted to the mobile device 100 in accordance with particular, usually predetermined, communication protocols and parameters, under control of its controller. The fixed transceiver equipment similarly demodulates and possibly decodes and decrypts, if necessary, any communication signals received from the mobile device 100 within its cell. Communication protocols and parameters may vary between different nodes. For example, one node may employ a different modulation scheme and operate at different frequencies than other nodes.

For all mobile devices 100 registered with a specific network, permanent configuration data such as a user profile is stored in the HLR 212. The HLR 212 also contains location information for each registered mobile device and can be queried to determine the current location of a mobile device. The MSC 210 is responsible for a group of location areas and stores the data of the mobile devices currently in its area of responsibility in the VLR 214. Further, the VLR 214 also contains information on mobile devices that are visiting other networks. The information in the VLR 214 includes part of the permanent mobile device data transmitted from the HLR 212 to the VLR 214 for faster access. By moving additional information from a remote HLR 212 node to the VLR 214, the amount of traffic between these nodes can be reduced so that voice and data services can be provided with faster response times and at the same time requiring less use of computing resources.

The SGSN 216 and the GGSN 218 are elements added for GPRS support, namely packet switched data support, within GSM. The SGSN 216 and the MSC 210 have similar responsibilities within the wireless network 200 by keeping track of the location of each mobile device 100. The SGSN 216 also performs security functions and access control for data traffic on the wireless network 200. The GGSN 218 provides internetworking connections with external packet switched networks and connects to one or more SGSN's 216 via an Internet Protocol (IP) backbone network operated within the network 200. During normal operations, a given mobile device 100 must perform a “GPRS Attach” to acquire an IP address and to access data services. This requirement is not present in circuit switched voice channels as Integrated Services Digital Network (ISDN) addresses are used for routing incoming and outgoing calls. Currently, all GPRS capable networks use private, dynamically assigned IP addresses, thus requiring the DHCP server 220 connected to the GGSN 218. There are many mechanisms for dynamic IP assignment, including using a combination of a Remote Authentication Dial-In User Service (RADIUS) server and a DHCP server. Once the GPRS Attach is complete, a logical connection is established from a mobile device 100, through the PCU 208, and the SGSN 216 to an Access Point Node (APN) within the GGSN 218. The APN represents a logical end of an IP tunnel that can either access direct Internet compatible services or private network connections. The APN also represents a security mechanism for the network 200, insofar as each mobile device 100 must be assigned to one or more APNs and mobile devices 100 cannot exchange data without first performing a GPRS Attach to an APN that it has been authorized to use. The APN may be considered to be similar to an Internet domain name such as “myconnection.wireless.com”.

Once the GPRS Attach operation is complete, a tunnel is created and all traffic is exchanged within standard IP packets using any protocol that can be supported in IP packets. This includes tunneling methods such as IP over IP as in the case with some IPSecurity (IPsec) connections used with Virtual Private Networks (VPN). These tunnels are also referred to as Packet Data Protocol (PDP) Contexts and there are a limited number of these available in the network 200. To maximize use of the PDP Contexts, the network 200 will run an idle timer for each PDP Context to determine if there is a lack of activity. When a mobile device 100 is not using its PDP Context, the PDP Context can be de-allocated and the IP address returned to the IP address pool managed by the DHCP server 220.

Referring now to FIG. 7, shown therein is a block diagram illustrating components of an example configuration of a host system 250 that the mobile device 100 can communicate with in conjunction with the connect module 144. The host system 250 will typically be a corporate enterprise or other local area network (LAN), but may also be a home office computer or some other private system, for example, in variant implementations. In this example shown in FIG. 7, the host system 250 is depicted as a LAN of an organization to which a user of the mobile device 100 belongs. Typically, a plurality of mobile devices can communicate wirelessly with the host system 250 through one or more nodes 202 of the wireless network 200.

The host system 250 includes a number of network components connected to each other by a network 260. For instance, a user's desktop computer 262 a with an accompanying cradle 264 for the user's mobile device 100 is situated on a LAN connection. The cradle 264 for the mobile device 100 can be coupled to the computer 262 a by a serial or a Universal Serial Bus (USB) connection, for example. Other user computers 262 b-262 n are also situated on the network 260, and each may or may not be equipped with an accompanying cradle 264. The cradle 264 facilitates the loading of information (e.g., PIM data, private symmetric encryption keys to facilitate secure communications) from the user computer 262 a to the mobile device 100, and may be particularly useful for bulk information updates often performed in initializing the mobile device 100 for use. The information downloaded to the mobile device 100 may include certificates used in the exchange of messages.

It will be understood by persons skilled in the art that the user computers 262 a-262 n will typically also be connected to other peripheral devices, such as printers, etc. which are not explicitly shown in FIG. 7. Furthermore, only a subset of network components of the host system 250 are shown in FIG. 4 for ease of exposition, and it will be understood by persons skilled in the art that the host system 250 will include additional components that are not explicitly shown in FIG. 5 for this example configuration. More generally, the host system 250 may represent a smaller part of a larger network (not shown) of the organization, and may include different components and/or be arranged in different topologies than that shown in the example embodiment of FIG. 7.

To facilitate the operation of the mobile device 100 and the wireless communication of messages and message-related data between the mobile device 100 and components of the host system 250, a number of wireless communication support components 270 can be provided. In some implementations, the wireless communication support components 270 can include a message management server 272, a mobile data server 274, a contact server 276, and a device manager module 278. The device manager module 278 includes an IT Policy editor 280 and an IT user property editor 282, as well as other software components for allowing an IT administrator to configure the mobile devices 100. In an alternative example embodiment, there may be one editor that provides the functionality of both the IT policy editor 280 and the IT user property editor 282. The support components 270 also include a data store 284, and an IT policy server 286. The IT policy server 286 includes a processor 288, a network interface 290 and a memory unit 292. The processor 288 controls the operation of the IT policy server 286 and executes functions related to the standardized IT policy as described below. The network interface 290 allows the IT policy server 286 to communicate with the various components of the host system 250 and the mobile devices 100. The memory unit 292 can store functions used in implementing the IT policy as well as related data. Those skilled in the art know how to implement these various components. Other components may also be included as is well known to those skilled in the art. Further, in some implementations, the data store 284 can be part of any one of the servers.

In this example embodiment, the mobile device 100 communicates with the host system 250 through node 202 of the wireless network 200 and a shared network infrastructure 224 such as a service provider network or the public Internet. Access to the host system 250 may be provided through one or more routers (not shown), and computing devices of the host system 250 may operate from behind a firewall or proxy server 266. The proxy server 266 provides a secure node and a wireless Internet gateway for the host system 250. The proxy server 266 intelligently routes data to the correct destination server within the host system 250.

In some implementations, the host system 250 can include a wireless VPN router (not shown) to facilitate data exchange between the host system 250 and the mobile device 100. The wireless VPN router allows a VPN connection to be established directly through a specific wireless network to the mobile device 100. The wireless VPN router can be used with the Internet Protocol (IP) Version 6 (IPV6) and IP-based wireless networks. This protocol can provide enough IP addresses so that each mobile device has a dedicated IP address, making it possible to push information to a mobile device at any time. An advantage of using a wireless VPN router is that it can be an off-the-shelf VPN component, and does not require a separate wireless gateway and separate wireless infrastructure. A VPN connection can preferably be a Transmission Control Protocol (TCP)/IP or User Datagram Protocol (UDP)/IP connection for delivering the messages directly to the mobile device 100 in this alternative implementation.

Messages intended for a user of the mobile device 100 are initially received by a message server 268 of the host system 250. Such messages may originate from any number of sources. For instance, a message may have been sent by a sender from the computer 262 b within the host system 250, from a different mobile device (not shown) connected to the wireless network 200 or a different wireless network, or from a different computing device, or other device capable of sending messages, via the shared network infrastructure 224, possibly through an application service provider (ASP) or Internet service provider (ISP), for example.

The message server 268 typically acts as the primary interface for the exchange of messages, particularly email messages, within the organization and over the shared network infrastructure 224. Each user in the organization that has been set up to send and receive messages is typically associated with a user account managed by the message server 268. Some example implementations of the message server 268 include a Microsoft Exchange™ server, a Lotus Domino™ server, a Novell Groupwise™ server, or another suitable mail server installed in a corporate environment. In some implementations, the host system 250 may include multiple message servers 268. The message server 268 may also be adapted to provide additional functions beyond message management, including the management of data associated with calendars and task lists, for example.

When messages are received by the message server 268, they are typically stored in a data store associated with the message server 268. In at least some example embodiments, the data store may be a separate hardware unit, such as data store 284, that the message server 268 communicates with. Messages can be subsequently retrieved and delivered to users by accessing the message server 268. For instance, an email client application operating on a user's computer 262 a may request the email messages associated with that user's account stored on the data store associated with the message server 268. These messages are then retrieved from the data store and stored locally on the computer 262 a. The data store associated with the message server 268 can store copies of each message that is locally stored on the mobile device 100. Alternatively, the data store associated with the message server 268 can store all of the messages for the user of the mobile device 100 and only a smaller number of messages can be stored on the mobile device 100 to conserve memory. For instance, the most recent messages (i.e., those received in the past two to three months for example) can be stored on the mobile device 100.

When operating the mobile device 100, the user may wish to have email messages retrieved for delivery to the mobile device 100. The message application 138 operating on the mobile device 100 may also request messages associated with the user's account from the message server 268. The message application 138 may be configured (either by the user or by an administrator, possibly in accordance with an organization's information technology (IT) policy) to make this request at the direction of the user, at some pre-defined time interval, or upon the occurrence of some pre-defined event. In some implementations, the mobile device 100 is assigned its own email address, and messages addressed specifically to the mobile device 100 are automatically redirected to the mobile device 100 as they are received by the message server 268.

The message management server 272 can be used to specifically provide support for the management of messages, such as email messages, that are to be handled by mobile devices. Generally, while messages are still stored on the message server 268, the message management server 272 can be used to control when, if, and how messages are sent to the mobile device 100. The message management server 272 also facilitates the handling of messages composed on the mobile device 100, which are sent to the message server 268 for subsequent delivery.

For example, the message management server 272 may monitor the user's “mailbox” (e.g., the message store associated with the user's account on the message server 268) for new email messages, and apply user-definable filters to new messages to determine if and how the messages are relayed to the user's mobile device 100. The message management server 272 may also compress and encrypt new messages (e.g., using an encryption technique such as Data Encryption Standard (DES), Triple DES, or Advanced Encryption Standard (AES)) and push them to the mobile device 100 via the shared network infrastructure 224 and the wireless network 200. The message management server 272 may also receive messages composed on the mobile device 100 (e.g., encrypted using Triple DES), decrypt and decompress the composed messages, re-format the composed messages if desired so that they will appear to have originated from the user's computer 262 a, and re-route the composed messages to the message server 268 for delivery.

Certain properties or restrictions associated with messages that are to be sent from and/or received by the mobile device 100 can be defined (e.g., by an administrator in accordance with IT policy) and enforced by the message management server 272. These may include whether the mobile device 100 may receive encrypted and/or signed messages, minimum encryption key sizes, whether outgoing messages must be encrypted and/or signed, and whether copies of all secure messages sent from the mobile device 100 are to be sent to a pre-defined copy address, for example.

The message management server 272 may also be adapted to provide other control functions, such as only pushing certain message information or pre-defined portions (e.g., “blocks”) of a message stored on the message server 268 to the mobile device 100. For example, in some cases, when a message is initially retrieved by the mobile device 100 from the message server 268, the message management server 272 may push only the first part of a message to the mobile device 100, with the part being of a pre-defined size (e.g., 2 KB). The user can then request that more of the message be delivered in similar-sized blocks by the message management server 272 to the mobile device 100, possibly up to a maximum predefined message size. Accordingly, the message management server 272 facilitates better control over the type of data and the amount of data that is communicated to the mobile device 100, and can help to minimize potential waste of bandwidth or other resources.

The mobile data server 274 encompasses any other server that stores information that is relevant to the corporation. The mobile data server 274 may include, but is not limited to, databases, online data document repositories, customer relationship management (CRM) systems, or enterprise resource planning (ERP) applications.

The contact server 276 can provide information for a list of contacts for the user in a similar fashion as the address book on the mobile device 100. Accordingly, for a given contact, the contact server 276 can include the name, phone number, work address and email address of the contact, among other information. The contact server 276 can also provide a global address list that contains the contact information for all of the contacts associated with the host system 250.

It will be understood by persons skilled in the art that the message management server 272, the mobile data server 274, the contact server 276, the device manager module 278, the data store 284 and the IT policy server 286 do not need to be implemented on separate physical servers within the host system 250. For example, some or all of the functions associated with the message management server 272 may be integrated with the message server 268, or some other server in the host system 250. Alternatively, the host system 250 may include multiple message management servers 272, particularly in variant implementations where a large number of mobile devices need to be supported.

Alternatively, in some example embodiments, the IT policy server 286 can provide the IT policy editor 280, the IT user property editor 282 and the data store 284. In some cases, the IT policy server 286 can also provide the device manager module 278. The processor 288 of the IT policy server 286 can be used to perform the various steps of a method for providing IT policy data that is customizable on a per-user basis. The processor 288 can execute the editors 280 and 282. In some cases, the functionality of the editors 280 and 282 can be provided by a single editor. In some cases, the memory unit 292 can provide the data store 284.

The device manager module 278 provides an IT administrator with a graphical user interface with which the IT administrator interacts to configure various settings for the mobile devices 100. As mentioned, the IT administrator can use IT policy rules to define behaviors of certain applications on the mobile device 100 that are permitted such as phone, web browser or Instant Messenger use. The IT policy rules can also be used to set specific values for configuration settings that an organization requires on the mobile devices 100 such as auto signature text, WLAN/VoIP/VPN configuration, security requirements (e.g., encryption algorithms, password rules, etc.), specifying themes or applications that are allowed to run on the mobile device 100, and the like.

Many modifications and other example embodiments will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that various modifications and embodiments are intended to be included within the scope of the appended claims. 

1. A communications system comprising: a plurality of client devices configured to generate client processing jobs and each having a respective unique client identification (ID) associated therewith; a plurality of geographically spaced apart servers configured to process the client processing jobs and each having a respective unique server ID associated therewith; and a load balancer configured to receive the client processing jobs from the plurality of client devices, for each client processing job, generate a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server, and assign each client processing job to a respective server based upon the load balancing scores for the client processing job.
 2. The communications system of claim 1 wherein the separation metric corresponds to a number of network nodes between the requesting client device and each server.
 3. The communications system of claim 1 wherein the separation metric corresponds to a geographic distance between the requesting client device and each server.
 4. The communications system of claim 1 wherein the separation metric corresponds to a network latency between the requesting client device and each server.
 5. The communications system of claim 1 wherein the load balancer is configured to generate the respective load balancing score for each server based upon a hash of the server ID.
 6. The communications system of claim 5 wherein the load balancer is further configured to generate the respective load balancing score for each server based upon a hash of the server ID and the processing load metric.
 7. The communications system of claim 6 wherein the load balancer is further configured to generate the respective load balancing score for each server based upon a hash of the client ID, the separation metric, and the hash of the server ID and the processing load metric.
 8. The communications system of claim 1 wherein the load balancer is configured to assign each client processing job to a respective server having a highest load balancing score from among the load balancing scores for the client processing job.
 9. The communications system of claim 1 wherein the load balancer is configured to assign each client processing job to a respective server having a lowest load balancing score from among the load balancing scores for the client processing job.
 10. The communications system of claim 1 wherein the processing jobs comprise Internet access jobs.
 11. The communications system of claim 1 wherein at least some of the plurality of client devices comprises mobile wireless communications devices.
 12. The communications system of claim 1 wherein at least some of the plurality of client devices comprise cellular communication devices.
 13. A load balancer for use with a plurality of client devices configured to generate client processing jobs and each having a respective unique client identification (ID) associated therewith, and a plurality of geographically spaced apart servers configured to process the client processing jobs and each having a respective unique server ID associated therewith, the load balancer comprising: a client device interface module configured to receive the client processing jobs from the plurality of client devices; and a server interface module coupled to the client device interface module and configured to for each client processing job, generate a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server, and assign each client processing job to a respective server based upon the load balancing scores for the client processing job.
 14. The load balancer of claim 13 wherein the separation metric corresponds to a number of network nodes between the requesting client device and each server.
 15. The load balancer of claim 13 wherein the separation metric corresponds to a geographic distance between the requesting client device and each server.
 16. The load balancer of claim 13 wherein the separation metric corresponds to a network latency between the requesting client device and each server.
 17. The load balancer of claim 13 wherein the load balancer is configured to generate the respective load balancing score for each server based upon a hash of the client ID, the separation metric, and a hash of the server ID and the processing load metric.
 18. A load balancing method for a plurality of client devices configured to generate client processing jobs and each having a respective unique client identification (ID) associated therewith, and a plurality of geographically spaced apart servers configured to process the client processing jobs and each having a respective unique server ID associated therewith, the method comprising: receiving the client processing jobs from the plurality of client devices at a client device interface module; for each client processing job, generating a respective load balancing score for each server based upon the client ID of the client device requesting the client processing job, the server ID of each server, a processing load metric for each server, and a separation metric corresponding to a separation between the requesting client device and each server at a server interface module; and assigning each client processing job to a respective server at the server interface module based upon the load balancing scores for the client processing job.
 19. The method of claim 18 wherein the separation metric corresponds to a number of network nodes between the requesting client device and each server.
 20. The method of claim 18 wherein the separation metric corresponds to a geographic distance between the requesting client device and each server.
 21. The method of claim 18 wherein the separation metric corresponds to a network latency between the requesting client device and each server.
 22. The method of claim 18 wherein generating the respective load balancing score for each server comprises generating the respective load balancing score based upon a hash of the server ID.
 23. The method of claim 22 wherein generating the respective load balancing score for each server comprises generating the respective load balancing score based upon a hash of the server ID and the processing load metric.
 24. The method of claim 23 wherein generating the respective load balancing score for each server comprises generating the respective load balancing score based upon a hash of the client ID, the separation metric, and the hash of the server ID and the processing load metric. 